One of Princess Diana’s closest friends Rosa Monckton hit out after TV chiefs snubbed a plea from Diana’s brother Charles to scrap Sunday’s documentary, based on film of the princess chatting to voice coach Peter Settelen.

Rosa said: “It’s completely inappropriate. How intrusive is this? It doesn’t matter that it was 20-odd years ago.

“Think of the hurt they are causing to her family, to her sons.”

Royal author Ingrid Seward said: “This is wrong. I think Diana is being exploited.

“The programme makers don’t give a toss who they hurt.

“I think it’s remarkable any TV station would stoop that low. It really is lowest common denominator TV.”

Knife horror

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And Patrick Jephson, Diana’s former private secretary, said: “I think it’s a programme that William and Harry should see because I think they will see a side of their mother that they themselves endorse.

Five of the tapes, which Diana’s aides urged her not to make, remain missing

“Peter was not her priest, doctor, therapist or lawyer.

“Diana was not disclosing bed-pillow confidences and the tapes were not secretly recorded.

“The issues which her concerns raised at the time, are as valid today as they were over 20 years ago, no matter how inconvenient or embarrassing it may be for the Royal Family or the establishment to have to deal with them.”

Settelen appeared in three Corrie episodes and devised the show Through The Keyhole.